This invention relates to precision control of a flow of fluid in fluid conducting lines, and applies particularly, though not exclusively, to the control of gaseous fuel to an internal combustion engine. Still more specifically, the invention relates to the control of fuel supply to internal combustion engines by means of electronic digital controls.
Two major problems are encountered today in the design of internal combustion engines and fuel systems therefor, viz., shortage and consequent high cost of gasoline and other liquid fuels with the attendant need to minimize fuel consumption, and the pollution of the environment with the attendant need to reduce the emission of noxious gases. One of the requirements arising out of these needs is that of accurate control of fuel supply in response to operating conditions and engine parameters.
One approach to the alleviation of the above-noted problems is the use of gaseous fuels such as natural gas (methane) and propane which show great promise as an alternative to gasoline as a power source for motor vehicles. It has been recognized that the increased use of gaseous fuels for internal combustion engines would reduce the amount of oil which must be imported into countries such as Canada and the United States. There is at present a sufficient supply of gaseous methane and propane to permit such expanded use. The principal source of methane is now natural gas. However, it can be produced from coal and waste biological products which are renewable. Methane and propane are also attractive because they produce less polluting exhaust products.
Italy pioneered extensive use of natural gas in motor vehicles, and consequently most of the conversion kits available in North America are direct Italian imports, or copies of the Italian designs. The known designs are based on a venturi mounted above the carburetor coupled to a vacuum actuated diaphragm regulator. Fundamental problems exist in this approach, problems that are not as apparent in the short range small vehicle environment of Europe, but are major obstacles to the acceptance of gas in North America.